Burner for producing gaseous mixtures in centrifugal fiber attenuating apparatus



INV ENTORS ATTORNEY M. LEVECQUE ETAL May 17, 1966 /I//A/Qaa ive-cous Mime/c' @enleva/nale United States Patent O BURNER FOR PRODUCING GASEOUS MIXTURES IN CENTRIFUGAL FIBER ATTENUATING AP- PARATUS Marcel Levecque, Saint-Gratien, and Maurice Charpentier,

Rantigny, France, assignors to Compagnie de Saint- Gobain, Neuilly-sur-Seine, France, a corporation of France Filed Dec. 27, 1961, Ser. No. 162,436 Claims priority, application France, Jan. 5, 1961,

9 claims. (cl. 65-14) The present invention relates to internal combustion burners having a combustion chamber into which the gaseous combustible mixture is conducted after passage through a grating, and from which the combustion gases escape through an expansion orifice.

It has been established that, when such burners are fed by a gas with low speed of combustion, serious difficulties are encountered. This is particularly the case when use is made of certain gaseous mixtures having a combustible element with high caloriiic power, in particular, gas with a high proportion of methane, such as natural gas. In this case, the burner flame does not cling to the grating, but is unstable, this instability manifesting itself in an extremely noisy or blustery operation of the burner, which often results-in its extinguishment. These effects are particularly conspicuous in the case where it is desired to obtain high speeds of the vburned gases upon departure from the burner, by reason of the relatively slow speed of combustion of these gases. The instability of the ame is thus much more marked, and the burner, in effect, can notbe maintained in a kindled state.

It is the object of the invention to improve these burners, particularly to permit the attainment of a stable and silent combustion with a flame clinging constantly to the grating, while burning a gaseous mixture, the cornbustible element of which is constituted by a gas of high caloric power, for example, refined natural gas of high methane content up to 96%.

According to one characteristic of the invention there is provided two gratings at the inlet for the combustiblecomburent or combustible gaseous mixtures in the combustion chamber. Oneof these gratings, which is located at the side of thegas intake, is similar to the known type of grating, and the other, placed inside the combustion chamber, is located near the first. Of course, this second grating is formed of elements capable of resisting the high temperatures attained in the combustion chamber. y

It has been established that the presence of this second' grating, by creating whirling and eddy movements, is'responsible for obtaining perfect stabilityof the llame, which remains localized inthe zone near the gratings.

In one particularly advantageous embodiment, the seclond grating is formed of a plurality of silica tubes disposed in parallel, with the plane passing through their axes being itself parallel to the plane of the first grating. This arrangement facilitates the passage of the 'gases in the chamber of the burner while creating whirling currents which assure the stability of the flame.

According to another characteristic of theinvention, provision is made to introduce the gaseous mixture in contactiwith the -rst grating in such a way that this bringing in contact is realized in a regular and homogeneous manner over the entire surface of the grating. For this purpose the invention provides giving to the inlet passage of the gas mixture a form which flares or spreads in the part of said passage approaching the grating.

Moreover, it has been established that it is necessary to ICC maintain the grating located at the side of the supply of the gas mixture, at as high a temperature as possible. For this purpose, the invention contemplates, and this constitutes another characteristic of the invention, the location of this grating in such a way that it is not noticeably cooled bythe walls of the intake passage, and more particularly by the cooling circuit which `may exist in these walls. According to one form of this improvement, the lirst grating, instead of beingadjacent with the end of the intake passage, is located somewhat farther on, nearer the second grating, and while `a cooling circuit exists, such fa shape is given to :the conduit for the cooling agent, that the cooling effect on the grating is noticeably reduced.

It has also been established that it is advantageous to maintain the -iirst grating at a high temperature at the side of the combustion chamber. It is therefore provided, according to another characteristic of the invention, that this grating be covered with a thin coating of a substance with high heat-absorptive power. In the case of metallic gratings, they can be covered with an oxide slip obtained, for example, by a mixture of silicate of soda and sand. Also, the metal of the grating may be oxidized before its utilization.

The invention likewise contemplates the application of burners embodying all or part of the improvements described above, to the production of gases lused for the manufacture of fibers from mineral or organic materials in the viscous state, and in particular, glass fibers, according to the process which consists in subjecting the filaments of melted material projected through orifices provided at the periphery of a hollow body rotating about its axis to the action of high temperature gases. The action of these high temperature gases at high speed, which escape from .the expansion orifice of a combustion chamber, has the effect of changing the filaments of material projected through the orifices of the rotating body into tine fibers.

In this application of the invention, the burner is of annular shape and is disposed coaxially with respect to the rotating body. The expansion orice itself is constituted by a continuous slot or a number of slots, this slotl or slots being themselves coaxial to the rotary body and the gaseous currents at high temperature and high speed which escape from the annular slot pass along the peripheral band of said body along its entire height.

The utilization of such a burner is particularly advan-v tageous in this application, since it permits the realization of an oxidizing combustion, aud obtaining at the exit, that is, at the edges of the burner, gases having a constant speed and temperature over the entire periphery. The result is that the peripheral band or wall of the rotating centrifuge is raised to a homogeneous temperature over its whole periphery and that, on the other hand, the action of the gases on the fibers projected through'the orifices of the peripheral wall is identical at all points. Hence, a uniform drawing-out action is had.

which results in obtaining fibers having substantially the same diameter.

Embodiments of a burner according to the invention are described below by way `of illustration, in conjunction with the accompanying drawing, wherein:

FIG. 1 is a vertical section of the burner;

FIG. 2 is a perspective View of a modification of the burner of the type shown in FIG. 1, featuring a nozzle for the intake of the combustible-comburent mixture; and

FIG. 3 is a vertical section with some parts in elevation of a burner according to the invention applied to the manufacture of glass fibers by a centrifuging operation.

In the accompanying drawing is shown the' combustion chamber 1 of the burner provided with the expansion orifice 2 for the combustion gases, the edges of which are cooled by circulation of a cooling liquid through passages 5. The combustion chamber is insulated from its housing 3 by refractory linings 4.

An apertured plate grating 6 is provided at the inlet to the combustion chamber, and this first grating 6 is arranged in the manner in which such gratings are provided in known burners of this type. Also, a second grating 7 is placed in the combustion chamber adjacent to grating 6. Grating 7 may be formed of a plurality of silica tubes disposed in parallel, and the axes of which are located in a plane parallel to grating 6,

The tubes constituting grating 7 can be sealed in the refractory lining without the interior thereof being traversed by fluids. Nevertheless, when gaseous mixtures having particularly low combustion speeds are used, or when the speed of the mixture passing over the grating is raised, it may be advantageous to have additional heat, which may be derived from heat inside tubes 7, and which may be produced by any appropriate means, such as the passage of hot fluids, electric heating, etc. Under other conditions, when the temperatures of the chamber are very high, it may be desirable, on the contrary, to cool tubes 7 by passage of fluid therethrough, to obtain good mechanical behavior of the grating. Thus, the tubes constituting the grating 7 may have free communication with air outside the combustion chamber, and thus be cooled by a circulation of air. The tubes 7 may also be connected in a fiuid circuit for the purpose of circulating a current of cooling fluid therethrough.

The grating 6 is formed in one piece 8 which is recessed to fit within the inlet opening of the combustion chamber, and is provided with a flanged shoulder 8a outside said chamber to facilitate the detachable mounting of the grating within the inlet opening. The inner face of said shoulder is in contact with one side of the housing 3 of the burner, and the outer face of the shoulder 8a is in contact with feed passage 9 for the combustible-comburent mixture. The inlet passage 9 is formed of a double wall to delineate a chamber 10 through which a cooling agent may pass. The inner wall 11 of this passage has a shape diverging toward grating 6. This arrangement of grating 6 and of the intake passage, results in decreasing of the cooling action on the grating on the one hand, and on the other hand, this arrangement seems to regulate theintake of the gaseous mixture, this intake or admission being homogeneous and substantially uniform over the entire surface of the grating 6.

In the embodiment shown in FIG. 2, a nozzle 12 is fastened to the inlet of passage 9, through which the cornbustible-comburent mixture is supplied into the apparatus. This nozzle widens from its inlet 12a toits outlet, the form and size of which correspond to those of the inlet of passage 9. This arrangement likewise results in obtaining a good homogenization of the admission of the gaseous mixture.

Since the sectional View shown in FIG. 2 is taken substantially across the mid-section of the inlet passage, it can be seen that the grill 6 is of substantially square dimensions.

FIG. 3 shows an example of the application of the burner according to the invention to the manufacture of fibers of mineral or organic materials in the viscous state, particularly glass fibers. This burner, with the features and characteristics described above, is annular in shape, and its-expansion orifice 2 is formed either as a -single continuous slot or as a plurality of arcuate slots. This burner is disposed coaxially with respect to a centrifuge body 13 rotating at high speed about its axis. The body 13 has a peripheral wall or band 15 provided with a large number of orifices 14 therein through which the melted material introduced into the interior of the rotating body is projected in the form of filaments by the action of centrifugal force. The gases of combustion which escape at high speed from slot 2 of the burner act uniformly on all these filaments when they leave the projection orifices 15 and transform them into fine fibers.

As shown in FIG. 3, the combustible-comburent mixture maybe introduced into the combustion chamber through a plurality of radially displaced inlet passages 9; for example, six of such inlets may be employed, displaced at sixty degree intervals.

We claim:

1. In an apparatus for projecting molten filaments from a rotary centrifuge, an internal combustion burner for combustible gaseous mixtures comprising a combustion chamber having an inlet opening in one wall thereof and a restricted outlet opening in another wall thereof from which the burnt gases escape at a very high speed and at high temperature, an apertured plate grating in said inlet opening, and a second grating within said combustion chamber separate and distinct from said plate grating and spaced slightly therefrom.

2. An apparatus as set forth in claim 1, including an inlet passage communicating with said inlet opening, said passage being fiared adjacent to said plate grating within said inlet opening, and a cooling chamber disposed at a portion of said passage remote from said plate grating to exert minimal cooling effects on the latter.

3. An apparatus as set forth in claim 1 wherein said plate grating is coated with a substance of high heat absorptivity.

4. An apparatus as set forth in claim 3 wherein said coating is an oxide slip.

5. An apparatus as set forth in claim 1, including an inlet passage communicating with said inlet opening, -said passage being fiared adjacent to said plate grating within said inlet opening, a double-walled inlet passage communicating with said inlet opening to form a cooling chamber between said walls of said passage, said cooling chamber being of lesser cross-section adjacent to said plate grating to minimize the cooling effects of said chamber on said plate grating.

6. In an apparatus for projecting molten filaments from a rotary centrifuge, yan internal combustion burner for combustible gaseous mixtures comprising a combustion chamber having an inlet opening in one wall thereof and a restricted outlet opening in another wall thereof from which the burnt gases escape at a very high speed and at high temperature, a substantially rectangular apertured plate grating mounted within said inlet opening, a second grating within said combustion chamber separate and distinct from said plate grating and -spaced slightly therefrom, an inlet passage communicating with said inlet opening having substantially the same cross-section as said plate grating, a nozzle connected to said inlet passage and of a cross-section conforming substantially to that of said inlet passage, and an intermediate conduit of smoothly fiaring cross-section between the inlet and outlet of said nozzle.

7. In an apparatus for projecting molten filaments from a rotary centrifuge, an internal combustion burner for combustible gaseous mixtures comprising a combustion chamber having an inlet opening in one wall thereof and an outlet opening in another Wall thereof, an apertured plate grating in said inlet opening, land a second grating within said combustion chamber adjacent to said plate grating and composed of a plurality of hollow heat exchange tubes arranged in parallel and disp'oed in a plane parallel to that ofthe plate grating.

8. In an apparatus for projecting molten laments from a rotary centrifuge, an internal combustion burner for combustible gaseous mixtures comprising a combustion chamber having an inlet opening in one Wall thereof and an outlet opening in another wall thereof, an apertured plate grating in said inlet opening, and a second grating within said combustion chamber adjacent to said plate grating and composed of a plurality of hollow heat exchange tubes arranged in parallel and disposed in a plane parallel to that of the plate grating, said tubes being open to the atmosphere to obtain a natural circulation of cooling fluid therethrough.

9. In an apparatus for projecting molten filaments from a rotary centrifuge, an internal combustion burner for combustible gaseous mixtures comprising a combustion chamber having an inlet opening in one wall there-of and an outlet opening in another wall thereof, an apertured plate grating in said inlet opening, and a second grating within said combustion chamber adjacent to said plate grating and composed of a plurality of hollow heat exchange tubes arranged in parallel and disposed in a plane parallel to that of the plate grating, said tubes being connected to a circulating Isystem containing heating or cooling uid.

References Cited by the Examiner UNITED STATES PATENTS Van Zandt.

Reichhelm 158--994 Fowler et al 106-75 X Lindahl 158-28 Hackley 117-99 X Levecque et al 65-14 FOREIGN PATENTS France.

DONALL H. SYLVESTER, Primary Examiner.

15 P. GOLDSTEIN, G. R. MYERS, Assistant Examiners. 

1. IN AN APPARATUS FOR PROJECTING MOLTEN FILAMENTS FROM A ROTARY CENTRIFUGE, AND INTERNAL COMBUSTION BURNER FOR COMBUSTIBLE GASEOUS MIXTURES COMPRISING A COMBUSTION CHAMBER HAVING AN INLET OPENING IN ONE WALL THEREOF AND A RESTRICTED OUTLET OPENING IN ANOTHER WALL THEREOF FROM WHICH THE BURNT GASES ESCAPE AT A VERY HIGH SPEED AND AT HIGH TEMPERATURE, AN APERTURED PLATE GRATING IN SAID INLET OPENING, AND A SECOND GRATING WITHIN SAID COMBUSTION CHAMBER SEPARATE AND DISTINCT FROM SAID PLATE GRATING AND SPACED SLIGHTLY THEREFROM. 